[英]Concurrently run two functions that take parameters and return lists?
I understand that two functions can run in parallel using multiprocessing
or threading
modules, eg Make 2 functions run at the same time and Python multiprocessing for parallel processes . 我知道两个函数可以使用
multiprocessing
或threading
模块并行运行,例如, 使2个函数同时运行,而Python对并行进程进行多处理 。
But the above examples only use print function. 但以上示例仅使用打印功能。 Is it possible to run functions that return a list in parallel in python, if so, how?
是否可以运行在python中并行返回列表的函数,如果可以,怎么办?
I've tried with threading: 我试过线程:
from threading import Thread
def func1(x):
return [i*i for i in x]
def func2(x):
return [i*i*i for i in x]
nums = [1,2,3,4,5]
p1 = Thread(target = func1(nums)).start()
p2 = Thread(target = func2(nums)).start()
print p1
print p2
but i got the follow error: 但我得到以下错误:
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 808, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 761, in run
self.__target(*self.__args, **self.__kwargs)
TypeError: 'list' object is not callable
None
None
Exception in thread Thread-2:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 808, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 761, in run
self.__target(*self.__args, **self.__kwargs)
TypeError: 'list' object is not callable
I've tried inputing args
parameter as a tuple, instead of a variable: 我尝试输入
args
参数作为元组,而不是变量:
import threading
from threading import Thread
def func1(x):
return [i*i for i in x]
def func2(x):
return [i*i*i for i in x]
nums = [1,2,3,4,5]
p1 = Thread(target = func1, args=(nums,)).start()
p2 = Thread(target = func2, args=(nums,)).start()
print p1, p2
but it only returns None None
, the desired output should be: 但它仅返回
None None
,所需的输出应为:
[out]: [OUT]:
[1, 4, 9, 16, 25] [1, 8, 27, 64, 125]
Thread's target function cannot return a value. 线程的目标函数无法返回值。 Or, I should say, the
return
value is ignored and as such, not communicated back to spawning thread. 或者,我应该说,
return
值将被忽略,因此不会传递回生成线程。 But here's a couple things you can do: 但是您可以执行以下几项操作:
1) Communicate back to spawning thread using Queue.Queue
. 1)使用
Queue.Queue
通讯回到生成线程。 Note the wrapper around the original functions: 请注意原始功能的包装:
from threading import Thread
from Queue import Queue
def func1(x):
return [i*i for i in x]
def func2(x):
return [i*i*i for i in x]
nums = [1,2,3,4,5]
def wrapper(func, arg, queue):
queue.put(func(arg))
q1, q2 = Queue(), Queue()
Thread(target=wrapper, args=(func1, nums, q1)).start()
Thread(target=wrapper, args=(func2, nums, q2)).start()
print q1.get(), q2.get()
2) Use global
to access result lists in your threads, as well as the spawning process: 2)使用
global
访问线程中的结果列表以及生成过程:
from threading import Thread
list1=list()
list2=list()
def func1(x):
global list1
list1 = [i*i for i in x]
def func2(x):
global list2
list2 = [i*i*i for i in x]
nums = [1,2,3,4,5]
Thread(target = func1, args=(nums,)).start()
Thread(target = func2, args=(nums,)).start()
print list1, list2
Target should only receive the function name. 目标应仅接收功能名称。 The parameters should be passed with the parameter "args".
参数应与参数“ args”一起传递。 I cannot paste the code because I am answering from my mobile phone... ;-)
我无法粘贴代码,因为我正在用手机接听... ;-)
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